It was a Friday night in September 1983, and I was 15 years old. My dad and brother were out, and my mum had a friend round. I was upstairs listening to music when I heard Mum's friend call up to me. I opened my door and leaned over the bannisters. She asked me what to do when Mum had an epileptic fit, so I explained about keeping her on her side and making sure she could breathe. She stared at me as if I'd said nothing.

"She's having one now, isn't she?" I said. She was.

Perhaps it was because I'd seen Mum's fits before that I wasn't panicked by it. Eyes open, but clearly unaware, she would shake, not wildly but as if desperately cold. Always, there was the chance of vomiting, so we would put her in the recovery position. Then, after a short while, she would be calm. She would sleep, and then, a bit dazed, wake up.

Not this time. This was lasting too long. My memory of calling for an ambulance is a calm one, but I have no idea whether or not I was. Things seemed to have slowed down.

The ambulance seemed a long time in coming, so I went outside to look for it. Eventually I saw it coming over the brow of the hill. No lights, no noise, no hurry. Fifty yards away, it turned right towards the old people's home. The numbers on our road were offset. We were 56, but opposite was 67 and down the road the old people's home was 57. They must have assumed it was for them.

I ran down the middle of the road. I never was the fastest runner, and certainly not in slippers. I only caught up at the end of the home's driveway. I shouted at the ambulance crew and told them to bring breathing equipment. I was in such a state by the time I got back that I could have used it myself.

Suddenly it was out of my hands. Just as the adrenaline kicked in, I had nothing to do. They moved quickly into the house, thinking: "Please, please. Do something." They told me to wait with the ambulance in case they received an important radio call. I fell for it, for a while at least. By the time I came to my senses the lounge door was closed. I couldn't go in.

The medics said later that even if she'd been in hospital, the fit she'd had was so severe it would have killed her anyway. I don't know to this day whether or not that's true. Maybe it was one of those things they tell children to soften the blow. I'd also been told that her epilepsy was mild, but maybe that was another one, to stop us being afraid.

After that point the details are blurred. Events seemed to speed up again. My father and brother were found and returned to the house. We were asked if we wanted to see her one last time. She looked tired, cold and distant. Not herself at all. She was 48.

My final memory of that night is of my dad coming to see me when I'd gone to bed. I don't recall what he said, but it must have been so hard for him. Who said anything, and what, to him? How must Mum's friend have felt? None of this occurred to me at the time.

Maybe it's an indication of how much I had taken my "normal" family life for granted before that night that I struggle to conjure it clearly now. I had always taken after my mum and I remember spending a lot of time with her. I was a sensitive child. I did well at school, but was bullied from time to time. My mum was as encouraging and supportive of my academic work as she was staunch in my defence. She was always on my side. I'd lost my greatest supporter and my most ardent protector. I felt numb, isolated.

Three days later I went back to school. What else was there to do but get on with it? At home it was as if a bridge between us all had been removed. The relative positions of my dad, my brother and me suddenly changed and I'm not sure any of us knew what we were meant to do. Life in a house full of men struggling to deal with their loss was difficult but we did our best.

I tried to do as much as I could to help keep the household going. It was only then that I realised how much Mum had done for us, and I bitterly regretted not doing more to help when she was around, but it was too late. Just as on that night, no matter what I did, I felt shamefully inadequate - and I loathed myself for it. The night Mum died, I'd tried to help, but couldn't. The failure, the judgment, was final. I was desolate and enraged by the injustice of it, but there was no one to appeal to, no redress. I'd bottle up my feelings until I could no longer contain them, then lash out at people. It was a vicious downward spiral.

My survival techniques were basic but effective. Emotionally I shut down, and up went the barricades. Self-pity became an easy refuge. Who could possibly understand what I'd been through that night?

Like my mum, I think I'm a gregarious soul at heart and being shut in like that jarred with me - but it was my protection. That tension would lead to sporadic attempts to reach out for something or someone. As I got older, I took relationships very seriously, perhaps too much so. I invested too much hope for happiness in them, when I wasn't happy myself. Sooner or later the unbearable fear of failure and isolation would become a self-fulfilling prophecy. Sometimes I hastened the end, just to wrest back control, to feel safe again.

My life had its fair share of good times and great people, but I couldn't settle; I couldn't commit. After my degree in Reading, I worked for the Open University in Milton Keynes, then took a masters in Brighton. I started a new career in IT in London, and joined bands here and there. Ultimately I avoided failure by not even trying and survived very efficiently, in an increasingly bleak manner. I existed rather than lived.

I admitted to myself that I was depressed in 2001. I'd thought it too weak previously. I started taking medication and, after a while, got some counselling. But I still felt stuck. In October 2002, a miserable weekend-long drinking binge left me unconscious for 24 hours, and then desperately calling friends in an unhinged, terrified panic. I didn't know what day it was. That did it. I was shocked by the extent to which I'd terrified myself.

I finally decided to change my mind.

Although I'd faced my depression I had steadfastly, from day one, refused to cite my mum's death as the cause of any of my problems. It seemed too obvious, too complacent. Above all it felt too much like blaming her. It wasn't the only reason but it was by far the major one, and to admit that was a huge relief. I allowed myself. It wasn't her fault. But it had happened, and it had hurt.

Slowly, steadily my appetite for life returned. The fear dissipated. I started trying new things, taking risks. I discovered a latent appetite for travel, now that I could see the world around me again.

As I got better I realised I'd been quite selfish over the years. Rather than berate myself for it, I tried to put more into my relationships with friends and family, not as penance but as a positive change. I missed out on knowing my mum for the real person she was, losing her just at the point when we were becoming friends. I realised I'd often treated my dad just as a parent, too. In the early days I was sometimes angry with him simply for not being Mum. One of the great rewards of overcoming depression has been to reinvigorate my relationship with him.

It would be too simplistic to say I'd have preferred that night not to have happened. To wish for a different life strikes me as futile escapism. It took me a long time to separate the rest of my mother's life from the fact of her death. To accept that life is flawed and transient has enabled me to enjoy it while it lasts. It's too easy - and too late - to recognise valuable things by their absence.

I sometimes wish I could remember her more clearly. I don't have enough pictures. I have only a vague idea of what she sounded like. I do have her hands - in every slender, crooked detail. I love the fact that I carry a physical reminder of my mum with me every day. I can think easily and happily of her nowadays, something I'm very glad to have retrieved. The memory of that horrific night will never change, but now it is reconciled, settled in a place of peace.